fifty, sixty, seventy
There are sixty (people) coming to the wedding.
We were about sixty people, I can't remember their names. (Key English Test; A2; Swiss German)
I started doing yoga in my sixties.
She is in her middle sixties, but still very active and lively. (First Certificate in English; B2; Dutch)
I still love all that music from the sixties.
Another problem is the demoli[t]ion of old houses that took place during the sixties. (First Certificate in English; B2; Swedish)